diff --git a/sys/netproto/802_11/wlan/ieee80211_power.c b/sys/netproto/802_11/wlan/ieee80211_power.c
--- a/sys/netproto/802_11/wlan/ieee80211_power.c
+++ b/sys/netproto/802_11/wlan/ieee80211_power.c
@@ -357,7 +357,7 @@
 	 * information.
 	 */
 	/* TU -> secs.  XXX handle overflow? */
-	age = IEEE80211_TU_TO_MS((ni->ni_intval * ic->ic_bintval) << 2) / 1000;
+	age = IEEE80211_TU_TO_MS(((uint64_t)ni->ni_intval * ic->ic_bintval) << 2) / 1000;
 	/*
 	 * Encapsulated frames go on the high priority queue,
 	 * other stuff goes on the low priority queue.  We use